A vehicle may include an engine having an oil pan containing a volume of oil. The oil may be pumped to various components of the engine to lubricate and/or cool the components. Engine oil can also be used to hydraulically actuate various systems such as a variable cam phasing system, a cylinder deactivation system, and/or a variable valve timing system, for example. Air and/or other gases can become entrained in the oil, which can adversely affect various properties of the oil such as viscosity, weight and/or capacity to retain heat, for example.